arch/powerpc/platforms/powernv/opal-irqchip.c

   1 /*
   2  * This file implements an irqchip for OPAL events. Whenever there is
   3  * an interrupt that is handled by OPAL we get passed a list of events
   4  * that Linux needs to do something about. These basically look like
   5  * interrupts to Linux so we implement an irqchip to handle them.
   6  *
   7  * Copyright Alistair Popple, IBM Corporation 2014.
   8  *
   9  * This program is free software; you can redistribute  it and/or modify it
  10  * under  the terms of  the GNU General  Public License as published by the
  11  * Free Software Foundation;  either version 2 of the  License, or (at your
  12  * option) any later version.
  13  */
  14 #include <linux/bitops.h>
  15 #include <linux/irq.h>
  16 #include <linux/irqchip.h>
  17 #include <linux/irqdomain.h>
  18 #include <linux/interrupt.h>
  19 #include <linux/module.h>
  20 #include <linux/of.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/kthread.h>
  23 #include <linux/delay.h>
  24 #include <linux/slab.h>
  25 #include <linux/irq_work.h>
  26
  27 #include <asm/machdep.h>
  28 #include <asm/opal.h>
  29
  30 #include "powernv.h"
  31
  32 /* Maximum number of events supported by OPAL firmware */
  33 #define MAX_NUM_EVENTS 64
  34
  35 struct opal_event_irqchip {
  36         struct irq_chip irqchip;
  37         struct irq_domain *domain;
  38         unsigned long mask;
  39 };
  40 static struct opal_event_irqchip opal_event_irqchip;
  41
  42 static unsigned int opal_irq_count;
  43 static unsigned int *opal_irqs;
  44
  45 static void opal_handle_irq_work(struct irq_work *work);
  46 static __be64 last_outstanding_events;
  47 static struct irq_work opal_event_irq_work = {
  48         .func = opal_handle_irq_work,
  49 };
  50
  51 static void opal_event_mask(struct irq_data *d)
  52 {
  53         clear_bit(d->hwirq, &opal_event_irqchip.mask);
  54 }
  55
  56 static void opal_event_unmask(struct irq_data *d)
  57 {
  58         set_bit(d->hwirq, &opal_event_irqchip.mask);
  59
  60         opal_poll_events(&last_outstanding_events);
  61         if (last_outstanding_events & opal_event_irqchip.mask)
  62                 /* Need to retrigger the interrupt */
  63                 irq_work_queue(&opal_event_irq_work);
  64 }
  65
  66 static int opal_event_set_type(struct irq_data *d, unsigned int flow_type)
  67 {
  68         /*
  69          * For now we only support level triggered events. The irq
  70          * handler will be called continuously until the event has
  71          * been cleared in OPAL.
  72          */
  73         if (flow_type != IRQ_TYPE_LEVEL_HIGH)
  74                 return -EINVAL;
  75
  76         return 0;
  77 }
  78
  79 static struct opal_event_irqchip opal_event_irqchip = {
  80         .irqchip = {
  81                 .name = "OPAL EVT",
  82                 .irq_mask = opal_event_mask,
  83                 .irq_unmask = opal_event_unmask,
  84                 .irq_set_type = opal_event_set_type,
  85         },
  86         .mask = 0,
  87 };
  88
  89 static int opal_event_map(struct irq_domain *d, unsigned int irq,
  90                         irq_hw_number_t hwirq)
  91 {
  92         irq_set_chip_data(irq, &opal_event_irqchip);
  93         irq_set_chip_and_handler(irq, &opal_event_irqchip.irqchip,
  94                                 handle_level_irq);
  95
  96         return 0;
  97 }
  98
  99 void opal_handle_events(uint64_t events)
 100 {
 101         int virq, hwirq = 0;
 102         u64 mask = opal_event_irqchip.mask;
 103
 104         if (!in_irq() && (events & mask)) {
 105                 last_outstanding_events = events;
 106                 irq_work_queue(&opal_event_irq_work);
 107                 return;
 108         }
 109
 110         while (events & mask) {
 111                 hwirq = fls64(events) - 1;
 112                 if (BIT_ULL(hwirq) & mask) {
 113                         virq = irq_find_mapping(opal_event_irqchip.domain,
 114                                                 hwirq);
 115                         if (virq)
 116                                 generic_handle_irq(virq);
 117                 }
 118                 events &= ~BIT_ULL(hwirq);
 119         }
 120 }
 121
 122 static irqreturn_t opal_interrupt(int irq, void *data)
 123 {
 124         __be64 events;
 125
 126         opal_handle_interrupt(virq_to_hw(irq), &events);
 127         opal_handle_events(be64_to_cpu(events));
 128
 129         return IRQ_HANDLED;
 130 }
 131
 132 static void opal_handle_irq_work(struct irq_work *work)
 133 {
 134         opal_handle_events(be64_to_cpu(last_outstanding_events));
 135 }
 136
 137 static int opal_event_match(struct irq_domain *h, struct device_node *node)
 138 {
 139         return h->of_node == node;
 140 }
 141
 142 static int opal_event_xlate(struct irq_domain *h, struct device_node *np,
 143                            const u32 *intspec, unsigned int intsize,
 144                            irq_hw_number_t *out_hwirq, unsigned int *out_flags)
 145 {
 146         *out_hwirq = intspec[0];
 147         *out_flags = IRQ_TYPE_LEVEL_HIGH;
 148
 149         return 0;
 150 }
 151
 152 static const struct irq_domain_ops opal_event_domain_ops = {
 153         .match  = opal_event_match,
 154         .map    = opal_event_map,
 155         .xlate  = opal_event_xlate,
 156 };
 157
 158 void opal_event_shutdown(void)
 159 {
 160         unsigned int i;
 161
 162         /* First free interrupts, which will also mask them */
 163         for (i = 0; i < opal_irq_count; i++) {
 164                 if (opal_irqs[i])
 165                         free_irq(opal_irqs[i], NULL);
 166                 opal_irqs[i] = 0;
 167         }
 168 }
 169
 170 int __init opal_event_init(void)
 171 {
 172         struct device_node *dn, *opal_node;
 173         const __be32 *irqs;
 174         int i, irqlen, rc = 0;
 175
 176         opal_node = of_find_node_by_path("/ibm,opal");
 177         if (!opal_node) {
 178                 pr_warn("opal: Node not found\n");
 179                 return -ENODEV;
 180         }
 181
 182         /* If dn is NULL it means the domain won't be linked to a DT
 183          * node so therefore irq_of_parse_and_map(...) wont work. But
 184          * that shouldn't be problem because if we're running a
 185          * version of skiboot that doesn't have the dn then the
 186          * devices won't have the correct properties and will have to
 187          * fall back to the legacy method (opal_event_request(...))
 188          * anyway. */
 189         dn = of_find_compatible_node(NULL, NULL, "ibm,opal-event");
 190         opal_event_irqchip.domain = irq_domain_add_linear(dn, MAX_NUM_EVENTS,
 191                                 &opal_event_domain_ops, &opal_event_irqchip);
 192         of_node_put(dn);
 193         if (!opal_event_irqchip.domain) {
 194                 pr_warn("opal: Unable to create irq domain\n");
 195                 rc = -ENOMEM;
 196                 goto out;
 197         }
 198
 199         /* Get interrupt property */
 200         irqs = of_get_property(opal_node, "opal-interrupts", &irqlen);
 201         opal_irq_count = irqs ? (irqlen / 4) : 0;
 202         pr_debug("Found %d interrupts reserved for OPAL\n", opal_irq_count);
 203
 204         /* Install interrupt handlers */
 205         opal_irqs = kcalloc(opal_irq_count, sizeof(*opal_irqs), GFP_KERNEL);
 206         for (i = 0; irqs && i < opal_irq_count; i++, irqs++) {
 207                 unsigned int irq, virq;
 208
 209                 /* Get hardware and virtual IRQ */
 210                 irq = be32_to_cpup(irqs);
 211                 virq = irq_create_mapping(NULL, irq);
 212                 if (virq == NO_IRQ) {
 213                         pr_warn("Failed to map irq 0x%x\n", irq);
 214                         continue;
 215                 }
 216
 217                 /* Install interrupt handler */
 218                 rc = request_irq(virq, opal_interrupt, 0, "opal", NULL);
 219                 if (rc) {
 220                         irq_dispose_mapping(virq);
 221                         pr_warn("Error %d requesting irq %d (0x%x)\n",
 222                                  rc, virq, irq);
 223                         continue;
 224                 }
 225
 226                 /* Cache IRQ */
 227                 opal_irqs[i] = virq;
 228         }
 229
 230 out:
 231         of_node_put(opal_node);
 232         return rc;
 233 }
 234 machine_arch_initcall(powernv, opal_event_init);
 235
 236 /**
 237  * opal_event_request(unsigned int opal_event_nr) - Request an event
 238  * @opal_event_nr: the opal event number to request
 239  *
 240  * This routine can be used to find the linux virq number which can
 241  * then be passed to request_irq to assign a handler for a particular
 242  * opal event. This should only be used by legacy devices which don't
 243  * have proper device tree bindings. Most devices should use
 244  * irq_of_parse_and_map() instead.
 245  */
 246 int opal_event_request(unsigned int opal_event_nr)
 247 {
 248         if (WARN_ON_ONCE(!opal_event_irqchip.domain))
 249                 return NO_IRQ;
 250
 251         return irq_create_mapping(opal_event_irqchip.domain, opal_event_nr);
 252 }
 253 EXPORT_SYMBOL(opal_event_request);